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4 to 1 main sheet with 2 to 1 fine tune cascade #154031
09/04/08 04:16 PM
09/04/08 04:16 PM
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waynemarlow Offline OP
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Having loads of rope all over the boat from my 6 : 1 main sheet is annoying me a little. Has anybody tried a 4:1 plus a 2:1 cascade running along the boom. The plan would be to pull in as tight as needs and cleat the main sheet then fine tune using the 2:1 from the mid boom. If you worked it right the 2:1 would still allow enough to dump the main without having to release the main sheet 4:1.

Just an idea, comments please. <img src="http://www.catsailor.com/forums/images/graemlins/cool.gif" alt="" />

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Re: 4 to 1 main sheet with 2 to 1 fine tune cascade [Re: waynemarlow] #154032
09/04/08 04:35 PM
09/04/08 04:35 PM
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Edmonton, Alberta, Canada
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Wouldn't the 2:1 be the coarse trim and the 4:1 the fine trim? And are you also intending to increase to 8:1 advantage?

Re: 4 to 1 main sheet with 2 to 1 fine tune cascade [Re: waynemarlow] #154033
09/04/08 04:41 PM
09/04/08 04:41 PM

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I've sailed Ts with a similar set up and yes it does work. But I wouldn't recommend it. To many ropes. The best system I've used had the ends of the 2:1 split port and stbd from the boom and tied off onto the side stays. Put a small ball or stopper knot just outboard of the blocks at the forward end of the boom so the "lazy" sheet doesn't pull through. When you get the setup right the lazy sheet will have just enough slack to rest on the tramp.

You won't get 4:1 at the back it will have to be 3:1 or 5:1

Re: 4 to 1 main sheet with 2 to 1 fine tune cascade [Re: bobcat] #154034
09/04/08 04:43 PM
09/04/08 04:43 PM

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Quote
Wouldn't the 2:1 be the coarse trim and the 4:1 the fine trim? And are you also intending to increase to 8:1 advantage?


The 2:1 picks up the dead end of the 4:1 making it 8:1. As mentioned above, 4:1 doesn't work, it will be 3:1 or 5:1.

Re: 4 to 1 main sheet with 2 to 1 fine tune cascade [Re: ] #154035
09/05/08 03:51 AM
09/05/08 03:51 AM
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waynemarlow Offline OP
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"I've sailed Ts with a similar set up and yes it does work"

Sorry yes it will probably be 5:1 but then the cascade may not allow enough rope to feed through on the main sheet blocks to allow the main to twist off far enough in gusty conditions.

Having sailed with this system can you confirm that by releasing the 2:1 cascade the main can be dumped enough to prevent the occassional swim ?.

Thanks

Re: 4 to 1 main sheet with 2 to 1 fine tune cascad [Re: waynemarlow] #154036
09/05/08 04:37 AM
09/05/08 04:37 AM
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France
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With a 5:1 at the back I doubt you will have enough leverage to release enough in a gust. With a 3:1 it should be fine, as you would have to release the same amount of rope than you release today with your 6:1.

Your current main sheet is one of those dual speed thingy with a blocker ball right? I remember looking at this thing when I tried your boat trying to understand how it worked...

Re: 4 to 1 main sheet with 2 to 1 fine tune cascad [Re: pepin] #154037
09/05/08 05:31 AM
09/05/08 05:31 AM
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waynemarlow Offline OP
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It was a Harken Magic Block system which went from 4:1 to 7:1 by hauling in until one stopper hit the block then releasing slightly and then rehauling. Seemed to work alright but was too long in total due to the internal cascade. We and I do say we ( we spent a bored morning at Mumbles trying to understand how it worked )never quite worked out how it did what it did.

On the basis that I couldn't get enough block spacing we converted it to a makeshift 6:1 hence the question as to get 7:1 will mean buying new triple blocks. <img src="http://www.catsailor.com/forums/images/graemlins/cool.gif" alt="" />

Re: 4 to 1 main sheet with 2 to 1 fine tune cascade [Re: waynemarlow] #154038
09/05/08 05:51 PM
09/05/08 05:51 PM

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I can't remember ever doing a large scale dump to avoid a capsize upwind, that is what the tiller is for. Also with the proposed system the skipper will still hang onto the course main and/or the traveller, so that can be dumped at any time.

Re: 4 to 1 main sheet with 2 to 1 fine tune cascade [Re: ] #154039
09/06/08 08:12 AM
09/06/08 08:12 AM
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waynemarlow Offline OP
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I race single handed so it would have to be the fine tune that gets dumped <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

Re: 4 to 1 main sheet with 2 to 1 fine tune cascade [Re: waynemarlow] #154040
09/06/08 04:55 PM
09/06/08 04:55 PM

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If you race single handed don't do it. The hassle of letting go of one rope (course/traveller) so it can then wash overboard to then have to reach for another rope will be far more hassle than a slightly longer mainsheet.

My imaginary F16 (the one I've been threatening to build four quite a while) will have a tornado style internal cascade main, primarily because it will be much cheaper than the big blocks required to make a conventional 8:1 main.

Re: 4 to 1 main sheet with 2 to 1 fine tune cascade [Re: ] #154041
09/07/08 05:25 AM
09/07/08 05:25 AM
Joined: Jun 2001
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North-West Europe
Wouter Offline
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For anyone interested.

I've been thinking for quite some time about a different path to make mainsail sheeting easier.

I've noticed that holding the sheet saps strength for when you want to sheet in. Basically, we are all strong enough to sheet the sail if we can fully relax afterwards. This means the line needs to be held in place by some system like a cleat or ratchet system that takes more of the line load then it currently does.

I'm not at all satisfied with the ratchet holding power on todays mainsheetsystems. The less then 90 degree wrap around the ratchetted sheeve does help here. I already use a tapered mainsheet and that was a large improvement in itself.

So two approaches are

-1- Make a full wrap around the standard ratchet with the sheet going to a small block on the boom just in front of the mainsheet system and then along the boom to a midboom sheeting point. The full wrap will at least improve the holding power by a factor of 2; which is alot

-2- Have the top block of the mainsheet include an auto ratchet (with also an auto ratched in the lower block). This way the mainsheet setup reflects the spi double ratchet setup and the holding power will be quite large but still have the sheet run very smoothly at lower line tensions (sheeting out).

Wouter


Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands

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